Positioning control method and apparatus

Abstract

A positioning control method and apparatus in which a fine movement mechanism is moved without exceeding a movable area so that positioning of a large amount of displacement can be attained with high accuracy and high-speed positioning from a point to a point with the same control method. A coarse movement mechanism (101) has a large amount of movement and low positioning accuracy and a fine movement mechanism (102) on the coarse movement mechanism has a small amount of movement and high positioning accuracy. A signal E4 based on a error signal C4 of a movement command signal A4 of a signal generator (104) and a displacement signal B4 representative of a displacement of an object to be positioned with respect to a fixed position detected by an absolute position detecting device (105) is supplied to the fine movement mechanism and a coarse movement command signal M4, produced by adding a signal representative of a relative displacement of the fine movement mechanism (102) with respect to the coarse movement mechanism (101) detected by a relative position detecting device (133) to the error signal C4, is supplied to the coarse movement mechanism (101) to thereby control respective movements.

We claim: 
     
       1. A positioning control method for controlling the position of an object mounted on a fine movement mechanism of a movement apparatus including a fine movement mechanism and a coarse movement mechanism, said coarse movement mechanism having a large amount of movement and low positioning accuracy and said fine movement mechanism having a small amount of movement and high positioning accuracy, comprising: adding an error signal obtained by subtracting a displacement signal representative of a displacement of the object with respect to a fixed position point of the apparatus from a movement command signal, to a relative displacement of said fine movement mechanism with respect to said coarse movement mechanism to produce a coarse movement command signal, inputting said coarse movement command signal to said coarse movement mechanism, and inputting said error signal to said fine movement mechanism.   
     
     
       2. A positioning control method for controlling a movement apparatus including a coarse movement mechanism which is moved with respect to an apparatus and a fine movement mechanism which is moved with respect to the coarse movement mechanism to position an object on the fine movement mechanism in a wide area with high accuracy, comprising: generating a movement command for designating a position of the object on the fine movement mechanism by a signal generator;   detecting an absolute displacement of the object on the fine movement mechanism with respect to a fixed point of the apparatus by absolute position detecting means;   detecting a relative displacement of the fine movement mechanism with respect to the coarse movement mechanism by relative position detecting means;   moving the coarse movement mechanism by a difference between an output of the absolute position detecting means and a sum of said movement command from the signal generator and an output of said relative position detecting means; and   moving the fine movement mechanism by an error signal obtained by subtracting the output of the absolute position detecting means from the movement command from the signal generator.   
     
     
       3. A positioning controller for controlling the position of an object mounted on a fine movement mechanism of a movement apparatus including a coarse movement mechanism having a large amount of movement and low positioning accuracy and the fine movement mechanism having a small amount of movement and high positioning accuracy, comprising: a signal generator for generating a movement command signal of the object to be positioned;   absolute position detecting means for detecting an absolute position of the object with respect to a fixed point of the apparatus and emitting a displacement signal representative of a displacement at the time;   relative position detecting means for detecting a relative displacement of the fine movement mechanism with respect to the coarse movement mechanism;   the fine movement mechanism being controlled on the basis of an error signal obtained by subtracting said displacement signal from said movement command signal; and   the coarse movement mechanism being controlled on the basis of a coarse movement command signal obtained by adding an output signal of said relative position detecting means to said error signal.   
     
     
       4. A positioning controller for controlling a movement apparatus including a coarse movement mechanism which is moved with respect to a fixed point of the apparatus and a fine movement mechanism which is moved with respect to said coarse movement mechanism for positioning an object on said fine movement mechanism in a wide area with high accuracy, comprising: a signal generator for generating a movement command for designating a position of said object on said fine movement mechanism;   an absolute position detecting means for detecting an absolute displacement of the object on said fine movement mechanism with respect to a fixed point of the apparatus;   a relative position detecting means for detecting a relative displacement of said fine movement mechanism with respect to said coarse movement mechanism;   a subtracting circuit means for generating an error signal obtained by subtracting an output of said absolute position detecting means from said movement command; and   an adder circuit means for adding an output of said relative position detecting means to said error signal, so that said coarse movement mechanism is controlled by an output of said adder circuit means and said fine movement mechanism is controlled by an output of said subtracting circuit means.